Oxyneurography: A new technique for the measurement of nerve oxygenation

Effects of Tourniquets in the Development of Pain States: a Novel Clinical Pilot Study and Review of Utilization of Tissue Oximetry to Measure Neural Ischemia

PURPOSE OF REVIEW

Approximately 20% of patients undergoing surgery develop persistent lower extremity pain following total knee arthroplasty. Animal studies have confirmed that prolonged tourniquet time increases the risk of endoneural ischemia and can mediate or modulate the development of chronic pain. The use of Near InfraRed Spectroscopy (NIRS) adjacent to nerve tissue, previously described as ONG has been shown to detect early neural compromise and has demonstrated clinical utility in carpal tunnel diagnosis.

RECENT FINDINGS

In this pilot study, we recruited 10 healthy adult volunteers to undergo oxyneurography (ONG) and sensory nerve conduction testing (sNCT). We performed testing on the upper and lower extremities in each individual. The tourniquet was applied followed by measurements of sNCT and ONG as described. We observed a significant drop in the mean ONG index at 3 and 5 min following tourniquet inflation in upper and lower extremities. Similar to raw ONG values, there was significant variability in sNCT measurements, which in general increased from baseline with tourniquet inflation. In the upper extremity, there was a significant increase in sNCT with tourniquet inflation, while in the lower extremity, there was a trend towards significance. The use of ONG can be supported as a diagnostic tool to detect nerve ischemia and to potentially reduce the incidence of tourniquet-mediated or -modulated neural ischemia and reduce the development of chronic post-tourniquet pain.

Value of oxyneurography, based on near infrared spectroscopy, in the diagnosis of carpal tunnel syndrome in comparison to provocative clinical diagnostic tests and nerve conduction studies

OBJECTIVE

Evaluation of the diagnostic utility of the oxyneurography (ONG) in diagnosing carpal tunnel syndrome (CTS).

METHODS

ONG examination of the median nerve was performed in 260 patients. The results were compared with nerve conduction studies and clinical provocative tests.

RESULTS

ONG index greater than or equal to 62% was found in 95.18% of the patients with no or minimal Nerve Conduction Study (NCS) changes (1-2 according to the Padua classification) but only in 1.69% of the patients with advanced NCS changes (Padua 3-6). The sensitivity and specificity of the ONG study i.e. 95.18% and 98.31%, respectively, were compared with standard clinical tests: Tinel sign (61.45% and 14.69%), Phalen test (34.94% and 45.20%), reverse Phalen test (81.93% and 34.46%) and carpal compression test (91.57% and 72.32%).

CONCLUSIONS

ONG index lower than 62% was indicative of CTS. ONG has higher sensitivity and specificity then other clinical tests and it is an accurate and reliable method for the diagnosis of CTS.

SIGNIFICANCE

Oxyneurography is a non-invasive, fast and safe study which may play role in the diagnosis of carpal tunnel syndrome.

Increased nerve vascularization detected by color Doppler sonography in patients with ulnar neuropathy at the elbow indicates axonal damage

INTRODUCTION

The aim of this study was to establish the prevalence of increased intraneural vascularization detected by ultrasonography (IVUS) in patients with ulnar neuropathy at the elbow (UNE) and to determine its relationship to clinical, ultrasonographic, and electrodiagnostic findings.

METHODS

High-resolution ultrasonography and color Doppler imaging were performed in 137 patients with confirmed UNE, 24 patient controls, and 70 healthy controls (HCs).

RESULTS

IVUS was found in 21 (15%) of 137 patients with UNE, in 1 (4%) of 24 patient controls, and in 0 of 70 HCs (P = 0.001). Patients with IVUS were more likely to have severe weakness (P = 0.01), severe atrophy of ulnar-innervated muscles (P = 0.008), axonal damage (P = 0.001), and more pronounced nerve enlargement (P = 0.03) than those without IVUS.

CONCLUSIONS

IVUS in the ulnar nerve can be detected in patients with UNE and is associated with nerve enlargement and clinical and electrodiagnostic severity. In addition, IVUS is associated with axonal damage.